The herbicide safener OTC (L-2-oxothiazolidine-4-carboxylic acid) increased the amount of reduced thiol compounds in sorghum [Sorghum bicolor (L.) Moench. ‘DK 427′] seedlings. When seedlings were grown in liquid culture medium containing 35S-OTC, the compound was metabolized to radiolabeled cysteine and glutathione. The addition of tridiphane [2-(3,5-dichlorophenyl)-2-(2,2,2-trichloroethyl)oxirane] increased conversion of 35S-OTC to cysteine and resulted in the formation of one additional 35S-labeled compound. When 35S-glutathione was injected into germinating seeds it was converted to 35S-cysteine and both thiols were subsequently found in roots and shoots. Seeds injected with 35S-OTC both translocated the compound to developing roots and shoots and metabolized 35S-OTC to cysteine and glutathione. Excised roots and shoots also metabolized 35S-OTC to the thiols. In an in vitro assay the enzyme 5-oxoprolinase converted OTC to cysteine.

The workup of the emergency patient with a raised anion gap metabolic acidosis includes assessment of the components of “MUDPILES” (methanol; uremia; diabetic ketoacidosis; paraldehyde; isoniazid, iron or inborn errors of metabolism; lactic acid; ethylene glycol; salicylates). This approach is usually sufficient for the majority of cases in the emergency department; however, there are many other etiologies not addressed in this mnemonic. Organic acids including 5-oxoproline (pyroglutamic acid) are rare but important causes of anion gap metabolic acidosis. We present the case of a patient with profound metabolic acidosis with raised anion gap, due to pyroglutamic acid in the setting of malnutrition and chronic ingestion of acetaminophen.